An image measurement device according to the present invention comprises: a stage on which a measurement object is mounted; an imaging device imaging the measurement object for a certain imaging range and outputting image information; a position control device that moves the imaging device to a plurality of measurement positions and scans in a scanning direction; and an arithmetic processing device that calculates a displacement of the measurement object. The imaging device is configured capable of imaging a preliminary measurement range broader than the certain imaging range. The arithmetic processing device, prior to a main measurement that measures the displacement of the measurement object at each measurement position, makes a preliminary measurement based on the image information corresponding to the preliminary measurement range, and sets a scanning range of the imaging device at each measurement position during the main measurement based on a result of this preliminary measurement.